Consolidated Tech Man - Holo-Krome

GLOSSARY OF TERMS
Tensile Strength - Force or stress required to break a fastener when pulled
in straight tension. When expressed as a force, lbs., it applies to a specific
size part. Expressed as a stress, psi, means the force is applied over a
specific area and it could apply to a range of sizes. For example, socket
screws from #0 to 1/2 inch can withstand an applied stress of 180,000 psi.
Stress Area - Theoretical area in the thread section of a fastener over which
the load is applied.
Yield Strength - This is the measure of the resistance of a material to plastic
(permanent) deformation. It is usually at a point of 0.2% permanent strain.
Torsion - Twisting force applied to a fastener during tightening.
Elongation - longitudinal stretching of a fastener caused by a tensile load
due either to tightening or to the external load.
Shear Strength - the resistance of a fastener to transverse loading. This
type of load should only be applied to a dowel pin or the unthreaded section
of a screw.
Rockwell Hardness - One method of measuring hardness of a metal,
generally related to the material tensile strength. Normally stated as “C”
scale readings, but may be taken as “A”, 30N or 15N scale readings when
limited penetration is desired. Limited penetration is required when checking
case hardness or thin parts.
Creep Strength - At elevated temperatures metal under stress elongates.
This elongation increases with time and temperature. To prevent failure it
is often necessary to change to heat resistant materials.
Fatigue Strength - Under variations in applied stress a fastener feels
internal stretching that can cause rupture after a specific number of cycles.
The number of cycles to failure for a specific load is the fatigue life of the
screw. In rigid assemblies preloading above the external load should
eliminate fatigue failure.
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